Abstract

For thermomechanical modelling of industrial vessels with the Finite Element Method (FEM), refractories should be seen, at macroscopic scale, as a homogeneous continua. However, at microscopic scale these refractory materials involve sophisticated micro-structures that mix several phases. Generally, these micro-structures are composed by a large amount of inclusions embedded in a brittle matrix that ensures the cohesion of the material. In some cases, these materials can advantageously exhibit complex non linear mechanical behaviors that results from the interactions between the different phases that compose the composite micro-structure. Following this idea, the macroscopic behaviour of these media may be predicted from the fine knowledge of their micro-structure. This paper proposes to study the impact of the diffuse damages that result from the thermal expansion mismatch between the phases in presence. These phenomenon involves a high amount of discontinuities and can not be tackled easily with the Finite Element Method (FEM). The Discrete Element Method (DEM) naturally accounts for discontinuities and is therefore a good alternative to the continuum approaches such as the FEM. However, the difficulty with DEM is to perform quantitative simulations because the mechanical quantities can't be described in terms of the classical continuum theory such as stresses or strains. This study will describe the approach used here to tackle this fundamental difficulty. The results given by the proposed approach are compared to experimental data obtained on simplified refractory materials. The results are compared in terms of macroscopic parameters such as the apparent Young's modulus and the thermal expansion coefficient that can be strongly affected by the presence of diffuse damages.